__security_init_cookie

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• Windows Embedded CE 6.0 R3

8/27/2008

Initializes the global security cookie.

Syntax

void __security_init_cookie(void);

Remarks

The global security cookie is used for buffer overrun protection in code compiled with /GS - Enable Security Checks, and in code that uses exception handling. Essentially, on entry to an overrun-protected function, the cookie is put on the stack, and on exit, the value on the stack is compared against the global cookie. Any difference between them indicates that a buffer overrun has occurred and results in immediate termination of the program.

Normally, __security_init_cookie is called by the CRT when it starts up. If you bypass CRT initialization (for example, by writing a DLL and specifying an entry-point with the /ENTRY linker option), then you must call __security_init_cookie yourself.

For more information about entry points, see CRT Entry Points.

The call to __security_init_cookie must be made before any overrun-protected function is entered; otherwise a spurious buffer overrun will be detected. Any function compiled with the /GS switch and containing a local buffer or exception handling (SEH or C++ EH) is a candidate for overrun protection.

If your entry point function does not require overrun protection, call __security_init_cookie at the beginning of that function. If the entry point function does require protection, create an entry point wrapper function to call __security_init_cookie, followed by your original entry point.

The following example demonstrates a correct way to call __security_init_cookie:

// Correct way to call __security_init_cookieDllEntryPoint(...) {   __security_init_cookie();   DllEntryHelper();}// Ensure that the original entry point is not inlined__declspec(noinline)void DllEntryHelper() {   ...   __try {      ...   } __except()... {      ...   }}

Requirements

See Also

Reference

/GS - Enable Security Checks

Concepts

CRT Entry Points
Linking to the CRT

Other Resources

EXEENTRY
DLLENTRY